Stair tread



FIG. 1 is a front perspective view of my design;

FIG. 2 is a front elevational view;

FIG. 3 is a rear elevational view;

FIG. 4 is a right side elevational view;

FIG. 5 is a left side elevational view;

FIG. 6 is a top plan view; and,

FIG. 7 is a bottom plan.

The broken line showing of environment is for illustrative purposes onlyand forms no part of the claimed design.

CLAIM The ornamental design for a stair tread, as shown and described.